In recent years, a light-emitting diode (LED) chip that emits blue or ultraviolet light by using a gallium nitride-based compound semiconductor has been developed. Further, by combining the LED chip with various fluorescent materials, light-emitting devices using LED have been developed which can emit light having color hues different from light emitted by the LED chip, such as white light. The light-emitting devices using LED have advantages of small size, little weight and power saving in comparison with light-emitting devices using hot filaments or gas discharges, and have been currently used widely as devices such as light-sources for indication, substitution for small-size light bulbs, and light-sources for liquid crystal display panels. The prior art devices of this type are disclosed in Japanese Laid-open Patent Publication No. 2000-208815, Japanese Laid-open Patent Publication No. 11-261114 and the like. The light-emitting devices using LED shown in these prior art documents have an arrangement in which a fluorescent material or a fluorescent-material-mixed resin is placed around the LED chip, with at least one portion touching the LED chip.
In the above-mentioned light-emitting device using LED, however, since the fluorescent material or the fluorescent-material-mixed resin is made in contact with the LED chip, that is, the light-emitting element, the material or resin tends to quickly deteriorate due to heat from the light-emitting element, and a problem results that the service life of the light-emitting device using LED depends on the service life of the fluorescent material or the fluorescent-material-mixed resin and dose not depend on the service life of the LED chip itself.
Moreover, prior art devices have been proposed (for example, see Japanese Laid-open Patent Publication No. 2000-101148), as shown in FIG. 32 and FIG. 33, in which a light-emitting element 20 connected to wires L and L is sealed by a transparent resin 40 into a shell shape. A fluorescent member 30 in the light-emitting device 100 (FIG. 32) is detachably attached to the outside of the element in contact therewith, and a fluorescent member 30 in the light-emitting device 101 (FIG. 33) is detachably attached thereto with a space 50 placed in a manner so as not to contact the element. However, in these cases, the fluorescent member 30, which has a light scattering property, is placed outside the optical member 40; consequently, even when an attempt is made to converge light rays from the light-emitting element 20 by using the optical member 40, and to align light rays in a predetermined direction, the light rays are scattered by the fluorescent member 30, and problems are caused that desired light-ray alignment is not achieved and it is not possible to efficiently apply light.
The present invention has been devised to solve the above-mentioned problems, and its objective is to provide a light-emitting device having a mixed-color light emitting function, which can lengthen the service life of a fluorescent material or a fluorescent-material-mixed resin that tends to deteriorate quickly, and also can easily form an optical structure that can align light rays outside the device.